[markdown] use build_runner to build js & wasm (#1969)

Author: kevmoo

.github/workflows/deploy_pages.yaml

@@ -26,28 +26,18 @@ jobs:
       - uses: dart-lang/setup-dart@e630b99d28a3b71860378cafdc2a067c71107f94
 
       # Build the markdown playground.
-      - name: "markdown: pub get"
-        run: dart pub get
+      - run: dart pub get
         working-directory: pkgs/markdown
-      - name: "markdown: build playground"
-        run: >
-          dart compile js -o example/app.dart.js
-          --minify --no-frequency-based-minification --no-source-maps
-          example/app.dart
+      - run: dart run build_runner build -o example:build --release
         working-directory: pkgs/markdown
 
       # Create the _site directory.
       - run: mkdir _site
-      - run: cp -r pkgs/markdown/example _site/markdown
-      - run: rm _site/markdown/*.dart
+      - run: cp -r pkgs/markdown/build _site/markdown
 
       # Deploy to GitHub Pages.
-      - name: setup pages
-        uses: actions/configure-pages@v5
-      - name: upload artifact
-        uses: actions/upload-pages-artifact@v3
+      - uses: actions/configure-pages@v5
+      - uses: actions/upload-pages-artifact@v3
         with:
           path: _site
-      - name: deploy to github pages
-        id: deployment
-        uses: actions/deploy-pages@v4
+      - uses: actions/deploy-pages@v4

pkgs/markdown/.gitignore

@@ -1,9 +1,4 @@
+# https://dart.dev/tools/pub/private-files
 .dart_tool
-.packages
-.pub
+build
 pubspec.lock
-doc/
-
-example/app.dart.js
-example/app.dart.js.deps
-example/app.dart.js.map

pkgs/markdown/build.yaml

@@ -0,0 +1,19 @@
+# See https://github.com/dart-lang/build/tree/master/build_web_compilers#configuration
+targets:
+  $default:
+    builders:
+      build_web_compilers|dart2js_archive_extractor:
+        options:
+          filter_outputs: false
+      build_web_compilers|entrypoint:
+        generate_for:
+          - example/**.dart
+        options:
+          compilers:
+            dart2wasm:
+              args:
+                - -O4
+                - --no-strip-wasm
+            dart2js:
+              args:
+                - -O4